[CUDA] Do not allow dynamic initialization of global device side variables.

In general CUDA does not allow dynamic initialization of
global device-side variables. One exception is that CUDA allows
records with empty constructors as described in section E2.2.1 of
CUDA 7.5 Programming guide.

This patch applies initializer checks for all device-side variables.
Empty constructors are accepted, but no code is generated for them.

Differential Revision: http://reviews.llvm.org/D15305

llvm-svn: 259592

1 files changed, 35 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaCUDA.cpp b/clang/lib/Sema/SemaCUDA.cpp
index 568c765..84fccd5 100644
--- a/clang/lib/Sema/SemaCUDA.cpp
+++ b/clang/lib/Sema/SemaCUDA.cpp
@@ -14,6 +14,7 @@
 #include "clang/Sema/Sema.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/ExprCXX.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/SemaDiagnostic.h"
 #include "llvm/ADT/Optional.h"
@@ -419,3 +420,37 @@ bool Sema::inferCUDATargetForImplicitSpecialMember(CXXRecordDecl *ClassDecl,
 
   return false;
 }
+
+bool Sema::isEmptyCudaConstructor(SourceLocation Loc, CXXConstructorDecl *CD) {
+  if (!CD->isDefined() && CD->isTemplateInstantiation())
+    InstantiateFunctionDefinition(Loc, CD->getFirstDecl());
+
+  // (E.2.3.1, CUDA 7.5) A constructor for a class type is considered
+  // empty at a point in the translation unit, if it is either a
+  // trivial constructor
+  if (CD->isTrivial())
+    return true;
+
+  // ... or it satisfies all of the following conditions:
+  // The constructor function has been defined.
+  // The constructor function has no parameters,
+  // and the function body is an empty compound statement.
+  if (!(CD->hasTrivialBody() && CD->getNumParams() == 0))
+    return false;
+
+  // Its class has no virtual functions and no virtual base classes.
+  if (CD->getParent()->isDynamicClass())
+    return false;
+
+  // The only form of initializer allowed is an empty constructor.
+  // This will recursively checks all base classes and member initializers
+  if (!llvm::all_of(CD->inits(), [&](const CXXCtorInitializer *CI) {
+        if (const CXXConstructExpr *CE =
+                dyn_cast<CXXConstructExpr>(CI->getInit()))
+          return isEmptyCudaConstructor(Loc, CE->getConstructor());
+        return false;
+      }))
+    return false;
+
+  return true;
+}